Hallicrafters S-108 IF transformer

Eric Lawson elawson at INFICAD.COM
Mon Dec 3 01:03:04 EST 2007

It turns out the secondary of the IF transformer is open.  I removed the
rivet and took the [completely fried] capacitor assembly out of the
transformer.  The shorted capacitor and the still good primary winding
were making the secondary look OK with an ohm meter.

Figuring I had ham handed the IF coil wires going to the terminals, I dug
out a 10X loupe and checked things over.  The wires are all still intact
and the solder joint looks OK as well [I even reflowed the solder, but no

I guess the transformer problem shouldn't surprise me as the failure
cascaded into the AGC sytem (open RF gain pot) and also made the 2nd IF
amp draw more current than the 470 ohm cathode resistor was happy about.

I took care of these two problems and put a 470pf cap in to couple the
signal into the 2nd IF amp.  The radio works, but the selectivity is
pretty bad...I would guess even with the exra IF transformer, the radio
still wouldn't be that useful during the CQ WW CW contest.... :-)


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